Heterochromatin content and early endosperm development in 42-chromosome spring triticale

Abstract

An analysis of several triticales (× Triticosecale Wittmack) from the International Maize and Wheat Improvement Center (CIMMYT) breeding program showed a strong correlation (r = 0.97, p ≤ 0.01) between test weight and the frequency of aberrant-nucleus formation in early endosperm development. The measurements of rye (Secale cereale L.) heterochromatin content indicated that, as compared with an average rye, in substituted triticales it was reduced by 21.4–49.8% and by 9.3 and 30% from that of two complete rye genome triticales analyzed. No correlation was observed between gross heterochromatin content and frequency of aberrant endosperm nucleus production and (or) test weight. However, both percentage heterochromatin and the production of aberrant endosperm nuclei were greatly reduced as compared with the average triticale previously analyzed. In addition, significant correlations were observed between the frequency of aberrant endosperm nuclei and the amount of telomeric heterochromatin on chromosomes 5R (r = −0.60, p ≤ 0.10) and 6R (r = 0.76, p ≤ 0.05). These results suggest that the presence or absence of telomeric heterochromatin on different rye chromosomes on triticale may have different effects on the regularity of early endosperm development and subsequent test weight at maturity. Furthermore, once the total amount of telomeric heterochromatin present on rye chromosomes was greatly reduced it appeared that other genetic factors became visibly involved in irregularities of endosperm development.