Identification And Cloning Of Related CDNA For Basal Spikelet Sterility Mutant In Wheat

Basal and apical spikelets sterility was important factors influencing grain number per ear. Apical spikelets sterility had been solved to a large extent for wheat cultivars. While most wheat varieties still have 1～2 sterile distal spikelets, and it's rare that all basal spikelets are fertile. So improving basal spikelets fertility, and finally increasing grain number per ear has become one of the key problems to increase wheat yield. We gained basal spikelets sterility mutant (BSS) via EMS inducing Shannong1186 which basal spikelets were completely fertile. In this study, we studied on it's agronomic traits, development of the spikelets and the genetic variation. DDRT-PCR (mRNA differential display PCR) technology was applied in order to clone the genes related to basal spikelets. The results were as follows:(1) The investigation on agronomic traits showed that 2-4 distal spikelets of all the 10 mutant lines were sterility. However, the distal spikelets of Shannong1186 were fertile. Compared with Shannong1186, grains per spike of all the 10 mutant lines decreased significantly; plant height, length of the first, second, fourth and fifth node from top of all the mutant lines increased significantly. It indicated that the increased length of multi nodes led to the increase of plant height; the width of flag leaf, penultimate leaf and the third leaf from top for the most mutant lines decreased significantly. There were some correlation among agronomic characters. There were significant positive correlation between plant height and distal sterility spikelets per spike, between length of the first node from top and distal sterility spikelets per spike, between length of the second node from top and distal sterility spikelets per spike. The correlation coefficients between flag leaf width and distal sterility spikelets per spike, between penultimate leaf width and distal sterility spikelets per spike, between Width of the third node from topdistal sterility spikelets per spike, between grains per spikedistal sterility spikelets per spike were significant negative at the 0.01 level.(3) Observation on spikelet morphological development showed that distal spikelets of the mutant began to degrade in tetrad stage. Pistils, stamens and ovaries of mutants became wilt and turn to illegibility organism. Degeneration was the reason why distal spikelets of mutants were sterility. Distal spikelets of Shannong1186 could develop normally in tetrad stage.(4) 305 EST-SSR were screened and 28 ones amplified different fragments between Shannong1186 and BSS mutant. The 28 polymorphic primer sets produced 133 amplified fragments, 2～6 fragments per primer pair, of which 43 (32.33%) were polymorphic.(5)mRNA differential display was used to analyze the differential expression of genes between Shannong1186 young panicles and BSS mutant young panicles. Seven differential fragments related to basal spikelets had been obtained: BSS₁～BSS₇. BSS₃ had highly homology (99%) with succinate dehydrogenase (SDH) in rice and Arabidopsis Thaliana. The results suggested that BSS₃ maybe accommodate metabolism of substance and energy by tricarboxylic acid cycle (TCA cycle), and finally regulated basal spikelets development in wheat. BSS₃ may belong to a broad regulated gene. BSS₄ was of highly homology with F-Box gene (ta94166) and protien (EAZ17658.1, EAY80184.1). F-Box was very important to function of B-type gene that controled petal and stamen development.