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  • Author or Editor: J. Cai x
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Uniformity in the height of main stem and tillers is a key factor affecting ideal plant type, a key component in super high-yielding rice breeding. An understanding of the genetic basis of the panicle layer uniformity may thus contribute to breeding varieties with good plant type and high yield. In the present study, a doubled haploid (DH) population, derived from a cross between indica rice variety Zhai-Ye-Qing 8 (ZYQ8) and japonica rice variety Jing-Xi 17 (JX17) was used to analyze quantitative trait loci (QTL) for panicle layer uniformity related traits. Six, four and three QTL were detected for the highest panicle height (HPH), lowest panicle height (LPH) and panicle layer dis-uniformity (PLD), respectively. qHPH-1-1 and qPLD-1 were located at the same interval on chromosome 1. The JX17 allele(s) of these QTL increased HPH and PLD by 2.57 and 1.26 cm, respectively. Similarly, qPLD-7 and qHPH-7 were located at the same interval on chromosome 7, where the ZYQ8 allele(s) increased HPH and PLD by 3.74 and 1.96 cm, respectively. These four QTL were unfavourable for panicle layer uniformity improvement because a decrease of the PLD was accompanied by decrease of the plant height. qPLD-6 and qLPH-6-1 were located at the same interval on chromosome 6, however here the JX17 allele(s) increased LPH, but decreased PLD, suggesting that this QTL was favourable for improvement of panicle layer uniformity. The markers identified in this study are potential for marker assisted breeding for the improvement of the panicle layer uniformity and ideal plant type.

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Based on the known GA20-oxidase (GA20ox) cDNAs of barley and wheat, oligonucleotide primers were designed to isolate GA20ox genes from genomic DNA of Dasypyrum villosum. A total of 19 clones were obtained. Each of them contained an open reading frame encoding a putative 40-KDa protein of 359 amino acid residues. Twenty-one SNPs and 4 InDels were found and could divide the 19 sequences into 2 classes, designated as DvGA20ox-1 and DvGA20ox-2, respectively. Q-PCR analyses showed that both DvGA20ox-1 and DvGA20ox-2 were in leaf blade, leaf sheath, stem, eustipes, root and developing spike. Similar expression levels were found between DvGA20ox-1 and DvGA20ox-2 in three stages. The total expression levels of DvGA20ox-1 and DvGA20ox-2 presented downtrend in leaf blade and ascend in stem, eustipes and developing spike along with the development of plants, respectively. However, they were firstly increased and then decreased in root from seeding stage to heading stage. These results revealed that the gene expression profile of DvGA20ox-1 and DvGA20ox-2 closely related to the growth and development of D. villosum.

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