Study On Barley Heterosis And Development Of Heterosis-relative Molecular Markers

In order to further understand mechanisms of barley heterosis and develop molecular markers related to barley heterosis, ten CMS sterile lines (A) and their respective maintainer lines (B) and eleven restore lines (R) were used as parent materials in this study. Hybrids produced by4×2and8×9were planted in experiment fields of Yangzhou University in2009and2010, respectively. And hybrids produced by8×6were planted in Fangqiang Farm, Shanghai Farm and experiment fields of Yangzhou University in2011. After maturity, competitive plants were choosed from every block randomly. And the traits height (PH), spike length excluding awns (SL), inter-node length (IL), spikes per plant (SP), kernels on main spike (KMS), kilo-grain weight (KW), kernel weight per plant (KWP) and dry matter weight per plant (DWP) were investigated. Then heterosis and its stability of hybrids and combining ability in every trait were analysed. The different express profiles between4×2hybrids and their parents were analysed by barley modified cDNA-AFLP technology. Then the transcript-derived fragments TDFs related to barley heterosis were recovered and sequenced. Based on the sequence information, the heterosis-relative molecular markers were developed. Then the effects of markers were estimated by8×9and8×6. The results showed that:(1) The different express profiles of eight hybrids and their parents in experiment I were analysed by barley cDNA-AFLP technology, total8538distinct bands were detected, among which3971(46.52%) bands was different between hybrids and their parents. Seven gene expression types were observed between hybrids and their parents, which included bands detected in hybrid and two parents (’111’type), band only detected in female parent (’100’type), band only detected in male parent (’001’type), band only detected in hybrid (’010’type), bands detected in female parent and hybrid (’110’type), bands detected in male parent and hybrid (’011’type) and bands detected in two parents (’101’type). Among the seven expression types, the last six types represented the differential gene expression between hybrid and its parents. After conjoint analyzing of different express fragments and barley heterosis, twenty three TDFs possibly related to barley heterosis was recovered and analyzed. Based of the exact or predicted function, the twenty-three TDFs were classified into three categories. First category was TDFs with functions to regulate barley growth and development. Second category was the TDFs involved in signal transduction and energy transfer. And the third category was unknown TDFs and no homology sequences TDFs.(2) Mid-parents heterosis was ubiquity among eight traits, but over-better-parent heterosis was only in some crosses. For all120hybrids in experiment II and III, the occurrence rate of significant mid-parents heterosis was57.60%. Among the significant mid-parents heterosis crosses, the ccurrence rate of positively significant Hm crosses was88.24%. However, the occurrence rate of significant over-better-parent heterosis was only25.94%. The heterosis was different between crosses and traits. Among the different traits, the occurrence rates of significant Hm corsses in PH, IL, SL, KMS and KW were higher, which were94.2%,84.2%,66.7%,62.5%and67.5%, respectively. While the occurrence rates of significant Hm corsses in SP, KWP and DWP were only17.5%,25.0%and37.5%. The occurrence rates of significant Hb crosses in IL, SL and KW were higher, which were59.2%,41.7%and59.2%, respectively. While the occurrence rates of significant Hb crosses in other triats were all lower than10%. The hybrids from the parents with different row type generated more significant heterosis over better parent than that from the parents with the same row type. For all traits, crosses such as A1×R3, A1×R10, A2×R9, A2×R10and A6×R3and so on were superior crosses.(3) Forty eight hybrids in experiment Ⅲ were planted three experiment fields Fangqiang Farm, Shanghai Farm and Yangzhou University, respectively. Then PH, SL, IL, SP, KMS, KW and KWP of hybrids and their parents were investigated and heterosis was analysed. For all traits, the occurrence rates of significant Hm and Hb in three sites were36.81%and8.23%, respectively. However, the occurrence rates were different between three sites. The occurrence rates of significant Hm were12.76%,32.03%and51.04%, respectively. And the occurrence rates of significant Hb were2.86%,2.86%and15.89%, respectively. Besides that, the degrees of heterosis were also different between three sites. The Hm of some corsses were only significant in one site or two sites. (4) For experiment Ⅱ and Ⅲ, the GCA variances in all traits and SCA variances of most traits were significant in twenty one parents. For one parent, the combining abilities were different among different traits. And the combining abilities were different betweent the two experiments. Based on GCA and SCA variances, the twenty one parents were clustered. And it is effective to estimate the use value of parents by this cluster method.(5) Based on the original sequence and homologous sequence information, twenty three molecular markers were developed. After estimation, four markers with better choosing effect were gained, which were TDF5-P, TDF6-P, TDF10-P and TDF12-P. The range of specificity of four markers to choose KW was43.48%～73.68%and the range of sensitivity was50.00%～78.95%. And the range of specificity of four markers to choose KWP was5.26%～56.52%and the range of sensitivity was33.33%～100%.