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Inheritance of waterlogging tolerance of barley (Hordeum vulgare L.)

M.X. Zhou1, Hongbin Li2, Neville Mendham2 and S. Salter1

1 Tasmanian Institute of Agricultural Research, P.O. Box 46, Kings Meadows, Tas 7250
2
School of Agricultural Science, University of Tasmania, PO Box 252-54, Hobart Tasmania 7001

Abstract

A complete diallel cross was made among six barley varieties. Three of them are Chinese varieties which showed better waterlogging tolerance, two are from Australia and one from Japan. Waterlogging treatment was conducted starting from the 3-leaf stage. Percentage of yellow leaf was recorded after waterlogging treatment. The data were then used to estimate variances (Vr) and covariances (Wr). A Wr/Vr graph showed that the inheritance of waterlogging tolerance followed an additive-dominant genetic model. Even though the graphic showed more recessive tolerant genes in one of the tolerant varieties and more dominant susceptible genes in the Japanese variety, the statistical test found no evidence of a dominance effect. Selection in early generations could be very efficient in discarding the plants with severe leaf chlorosis.

Media summary

Waterlogging tolerance in barley is genetically complex, but breeders should be able to make good progress by selecting tolerant plants, as the effects of the genes involved in this important character mainly add together to produce it.

Key Words

Barley, diallel analysis, waterlogging tolerance, leaf chlorosis

Introduction

Bringing tolerance of waterlogging into barley varieties is a very important breeding objective in high rainfall areas of southern Australia. To fulfil this aim, the most important step is to find waterlogging tolerant genes in barley germplasm. Takeda and Fukuyama (1986) tested 3457 varieties in the world collection by submerging 50 sterilized grains of each in deionized water in a test tube for 4 days at 25 deg C and subsequently determining their germination percentage after 4 days on moistened filter paper at 25C. The germination percentage ranged from 0 to 100. The collections from China, Japan and Korea contained many tolerant varieties (average indexes 71.6, 66.3 and 60.5, respectively) while those from North Africa, Ethiopia and southwest Asia showed few tolerant varieties (19.6, 13.8 and 13.2, respectively). The most tolerant varieties retained complete germinability after 8 days' soaking at 25 deg C. Qiu and He (1991), after testing 4572 barley varieties, reported that some showed a very high level of waterlogging tolerance germplasm. Fufa and Assefa (1995) reported some variation among genotypes in their tolerance to waterlogging and suggested locally adapted landraces could be major sources of tolerance. The understanding of genetic behaviour of waterlogging tolerance is also important for breeding varieties with waterlogging tolerance. Hamachi et al. (1989) found the frequency distributions of damage in F2s showed continuous variation. The realised heritability for flooding tolerance in 4 F4-F6 populations ranged from 0.12 to 0.48, based on percentage of dead leaf. Realised heritability estimates for 3 of the crosses ranged from -0.02 to1.06 and from -0.12 to 0.32 on the basis of the tolerance index of culm length and grain yield, respectively (Hamachi et al. 1990). In this experiment, six varieties with different waterlogging tolerance were selected to make a diallel cross to study the genetic behaviour of the tolerance genes.

Materials and method

Six selected varieties, TX9425, YYXT, DYSYH (from China), Franklin, Gairdner (from Australia)) and Naso Nijo (from Japan) were selected to make all the possible crosses between them. The three Chinese varieties showed much higher waterlogging tolerance than the other varieties (Zhou et al 2002). The six parents and the 15 F2 populations were sown in stainless steel tanks filled with the soil from Cressy Research Station, where waterlogging occurs regularly, during the 2003-4 summer at Mt Pleasant Laboratories in Launceston, Tasmania. There were two replications (tanks) of each variety. Starting from the 3-leaf stage, all the varieties were subjected to waterlogging (keeping the water level just above the soil surface) for 10 days. The percentage of yellow leaf area was recorded immediately after the termination of waterlogging.

Each variety or F2 population contained 10-12 plants. The yellow leaf percentage of each plant was scored separately after waterlogging and the average value of the 10-12 plants was used in final analysis.

Results and discussion

Difference in waterlogging tolerance of selected parents

Dead leaf percentage under excess soil moisture was thought to be the best criterion for selection for flooding tolerance in early generations because its heritability values are relatively constant and it is easy to measure (Hamachi et al. 1990) and was correlated with reduction of grain yield/plant and culm length (Hamachi et al. 1989). In this experiment, waterlogging caused significant chlorosis of the older leaves of all the varieties. Varieties showed significantly different tolerance to waterlogging (Table 1). Three Chinese varieties, TX9425 (12.6%), DYSYH (5.0%) and YYXT (7.0%) showed much less yellow leaf percentage than Franklin (43.9%), Gairdner (31.3%) and Naso Nijo (39.5%) (Figure 1).

Table 1. ANOVA of waterlogging tolerance of selected parents

Source of Variation

SS

df

MS

F

P-value

Varieties

2923.68

5

584.74

26.43

0.001

Replication

21.28

1

21.28

0.96

0.371

Error

110.63

5

22.13

   
           

Figure 1. Leaf chlorosis after waterlogging in two barley varieties (Franklin - left and YYXT - right)

In the crosses between waterlogging tolerant varieties and susceptible varieties, F2 populations showed extensive segregation in yellow leaf percentage. For example, the yellow leaf percentage of the F2 from the Franklin YYXT cross ranged from 5 to 80%. Tolerant varieties and crosses among them showed less variation between individuals. The yellow leaf percentage of DYSYH, YYXT and their F2 population all ranged from 5 to 10%.

Diallel analysis

Leaf chlorosis of all the parents and mean of F2 populations after waterlogging is shown in Table 2 (percentage of yellow leaf). Variances (Vr) and covariances (Wr) of each array in the diallel table were calculated and Wr was plotted against Vr (Figure 2).

Table 2. Half diallel data of yellow leaf percentage after waterlogging

 

TX9425

Naso Nijo

Franklin

Gairdner

YYXT

DYSYH

Mean

Vr

Wr

TX9425

12.7

31.2

25.6

24.1

15.5

8.9

19.7

73.8

132.9

Naso Nijo

 

38.0

41.8

33.0

27.6

23.3

32.5

45.4

107.7

Franklin

   

43.9

39.6

29.9

23.3

34.0

78.8

143.3

Gairdner

     

31.3

20.4

15.6

27.3

78.9

145.9

YYXT

       

7.0

6.9

17.9

97.7

162.5

DYSYH

         

5.0

13.8

66.5

134.9

             

Mean

73.6

137.9

Figure 2. The Wr/Vr graph for leaf chlorosis after waterlogging

As shown in Table 1, significant differences in waterlogging tolerance were found, indicating the significant additive effects. In Figure 2, the regression coefficient of Wr on Vr is 1.0362 which does not differ significantly from 1, indicating no evidence of non-independence in the effects of non-allelic genes. Thus the additive-dominance model is adequate to account for the behaviour of waterlogging tolerance involving these varieties. The lowest point is from the Naso Nijo array, indicating that Naso Nijo had the largest number of dominant alleles (waterlogging susceptible genes), while the highest is from the YYXT array which carried the smallest number of dominant alleles (waterlogging tolerant genes). However, due to the relatively small dominance effects, especially in the average value of F2 population with only half of dominance effect expressed, statistical analysis failed to detect the dominance effect, which was confirmed by Wr+Vr and Wr-Vr analysis (Table 3). For both Wr+Vr and Wr-Vr, there were no significant differences between arrays, indicating no significant dominance effect or non-allelic interaction.

Table 3. ANOVA of the effects of waterlogging on the number of green leaves per plant

 

Item

df

SS

MS

F

Wr+Vr

Between arrays

5

15368.5

3073.7

0.25

 

Within arrays

6

71641.9

11940.3

 

Wr-Vr

Between arrays

5

404.4

80.8

0.22

 

Within arrays

6

2173.6

362.3

 

Selecting for waterlogging tolerance

Based on leaf chlorosis, single plant selection for waterlogging tolerance could start as early as F2 since no significant dominance and non-allelic effects existed. As shown in this experiment, a very small variation in yellow leaf percentage was found among progeny of crosses between tolerant varieties, indicating that the same or similar genes are probably involved in each tolerant variety. The yellow leaf percentage for TX9425, YYXT and DDSYH are 5 - 20%, 5 -15% and 5%, respectively. The range of yellow leaf percentage for susceptible varieties was much greater among individuals. For example, the yellow leaf in Franklin ranged from 25 to 90%, even though most of individuals had 30 to 40%, which may be due to variation in plant development stage. Thus, individuals in F2 population with severe leaf chlorosis should almost always be susceptible while there may be a small number of tolerant plants which may not contain tolerant genes. For these tolerant plants, further evaluation in F3 is necessary.

Conclusion

Inheritance of waterlogging tolerance in barley is considered to be very complex. Based on the leaf chlorosis after waterlogging treatment, significant differences were found among varieties. Selected Chinese varieties had consistently better tolerance. A diallel cross study showed that the inheritance of waterlogging tolerance followed an additive-dominance genetic model with additive gene effects dominating. Selecting barley lines for waterlogging tolerance can be done as early as the first segregating generation. The most effective selection strategy is to discard the plants with severe leaf chlorosis.

References

Hamachi Y, Furusho M, and Yoshida T (1989). Heritability of wet endurance in malting barley. Japanese Journal of Breeding 39, 195-202.

Hamachi Y, Yoshino M, Furusho M and Yoshida (1990) Index of screening for wet endurance in malting barley. Japanese Journal of Breeding 40, 361-366.

Mather K and Jinks JL (1977) Introduction to biometrical genetics. Cornell University Press. Ithaca, New York.

Qiu JD and Ke YA (1991) Study of determination of wet tolerance of 4572 barley germplasm resources. Acta Agriculturae Shanghai 7, 27-32.

Takeda K and Fukuyama T (1986) Variation and geographical distribution of varieties for flooding tolerance in barley seeds. Barley Genetics Newsletter 16, 28-29.

Zhou MX, Xu RG, Chen DH, Huang ZL, Mendham NJ and Hossain M (2003) Effect of waterlogging on the growth of barley. 11th Australian Agronomy Conference, Geelong, Victoria.

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