Two Distinct Growth Types for Number of Developed Leaves, Heading Time, Culm and Panicle Lengths, and Internode Length within Near-isogenic Lines of Rice

Abstract

There are two growth types of plants for the number of developed leaves, heading time, and culm and panicle lengths within a population of a homozygous rice cultivar. However, this phenomenon has not been deeply investigated, because of lack of concrete data. Rice breeders and physiologists have paid little attention to it, regarding it as a genetically uncontrollable environmental variation. To study more details of the phenomenon, we grew two near-isogenic lines of rice with each one of the alleles for the Se1 locus conferring photoperiod sensitivity on chromosome 6 under natural long and short day-length conditions. In the line ER homozygous for the earliness allele Se1-e, and the line LR with the lateness allele Se1-u, N-leaf plants headed several days earlier than N+1-leaf plants. The N-leaf plants had shorter culms and longer panicles and were the upper-internode elongation type, whereas the N+1-leaf plants had opposite values of these characters. The proportion of these two kinds of plants changed in lines, plots and experiments. We discuss the meanings of this phenomenon from the viewpoints of rice cultivation to attain the uniform growth of plants, breeding to select individual plants with environmental variation, and fixation test to evaluate the uniformity needed as a cultivar.

Responses of earliness and lateness genes for heading to different photoperiods, and specific response of a gene or a pair of genes to short day length in rice

“…Kuriyama [15] reported that difference in the number of developed leaves among the early and late rice varieties, and decrease of DTH by each of the SD treatments was accompanied by a decrease in the number of developed leaves in each of the photosensitive varieties examined. The results of the present study indicate that the acceleration of heading by Se1-pat (t) observed from the 13.5-h photoperiod to the 10-h photoperiod conditions was accompanied by a decrease in the number of developed leaves in each of LF3 and LF2 (Tables 5 and 6), which is in accordance with the results of Yokoo et al [47]. The delay of heading caused by se-pat from T65wx to LF1 was accompanied by an increase of number of developed leaves in each of the SD and the 13.5-h photoperiod conditions.…”

“…Yokoo et al [47] indicated that Se1-u increases culm length, which is in accordance with the result regarding the Se1-pat (t) obtained by using LF3 and T65wx. On the other hand, Efx , the combination of Efx and Ef1 , that of Ef1 and m-Ef1 , and all of the three alleles reduced culm length; particularly, ER50 was the lowest.…”

Development of near-isogenic lines of Japonica-type rice variety Lijiangxintuanheigu as differentials for blast resistance

“…This region is also reported to contain the Photoperiod sensitivity 1 gene (Se1 = Hd1) (Yano et al 2000). Se1 plays a significant role in photoperiodic flowering, and it also affects internode elongation and culm length during panicle differentiation and heading (Yano et al 2000, Yokoo 2005). Therefore, the longer days-to-heading and panicle length of these two NILs might have been caused by the introgression of Se1 along with Piz-5 and Pi9.…”