影響碳水化合物自玉米穗軸轉移至子粒因素之研究3．果穗上、下位子粒於充實期間之糖類濃度與代謝酵素活性變化

Factors Affecting the Translocation of Carbohydrates from Cob to Kernels in Corn. 3. Carbohydrate Concentrations and Enzyme Activities of Apical and Basal Kernels during Kernel-Filling

林淑雰(S. F. Lin) ； 劉大江(D. J. Liu)

《中華農業研究》 42卷1期 (1993/03) Pp. 19-29

https://doi.org/10.29951/JARC.199303.0003

摘要

本試驗以單雜交玉米臺351號與臺農育365號為材料，兩者具相同母本及不同父本，且後者子粒充實性優於前者，於1986及1987年秋作進行田間試驗，在吐絲後連續針對果穗上位（自穗基算起之80~90%長度）及下位(20~30%)子粒與穗軸髓部組織取樣，分析糖類組成及數個與蔗糖代謝及澱粉合成有關酵素之活性，以瞭解基因型間與著生部位間子粒充實性差異的原因，供為進一步探討碳水化合物自玉米穗軸轉移至子粒因素研究之基礎。子粒葡萄糖濃度自吐絲後7日(7DAS)起快速下降，蔗糖與可溶性糖濃度則以13~20 DAS最高，但除蔗糖外，子粒充實初期之糖類組成均不足以說明充實能力或速率間的差異。上位子粒之sucrose synthase與ADPG-PPase活性多以臺農育365號較高，尤以後者之差異最為明顯，且上位子粒之活性均低於下位子粒，但由於各部位子粒兩個酵素的活性遠超過因應子粒充實速率的需要，尚難定論與影響子粒充實的機制有關。吐絲後初期上、下位穗軸髓部的澱粉濃度高達46.7與29.4%, TNC(total nonstructural carbohydrates)濃度亦高達89.9與77.6%，其後雖然下降，但均以上位髓部較高，成熟期髓部TNC濃度維持於20%以上，顯示碳水化合物可順利供應至穗軸，而由穗軸轉移至子粒的過程最可能影響子粒充實性狀。本試驗亦分析果穗髓部sucrose synthase、ADPG-PPase與invertase活性，認為除對吐絲後初期之澱粉累積具重要性外，穗軸三個酵素對碳水化合物轉運及子粒充實並不具有特殊意義。

關鍵字

玉米 ； 子粒充實 ； 醣類代謝 ； 酵素活性

並列摘要

Corn hybrids Tainung 351 (TNG 351) and Tainung Yu 365 (TNGY 365) were used as experimental material. The two hybrids have the same maternal inbred but different paternal inbreds. The latter hybrid was superior to the former in kernel-filling characters. Field experiments were conducted in the fall crop season of 1986 and 1987 to study carbohydrate composition and activities of related enzymes for kernels positioned at the apical and basal portions of the ear. Similar analyses had also been made on the pith tissue of the cob. Kernel glucose concentrations decreased sharply since 7 days after siking (DAS) while concentrations of sucrose and total soluble sugars peaked at 13-20 DAS. With the only exception of sucrose, changes in carbohydrate composition during early kernel-filling was not able to explain the differences in filling characters of apical kernels between the two genotypes. Activities of sucrose synthase and ADPG-PPase of apical kernels were generally higher for TNGY 365 than for TNG 351, with the latter enzyme to be the most significant. In addition, enzymatic activities of the basal kernels were higher than those of the apical kernels. However, their impact on kernel filling was considered insignificant as the measured activities were adequate to account for the dry matter accumulation rate in either apical and basal kermels. Starch concentrations of apical and basal pith tissue at 3 DAS were as high as 46.7 and 29.4%, respectively. Corresponding values of TNC concentrations were 89.9 and 77.6%. Although the concentrations decreased thereafter, they were higher for apical pith and TNC concentration at maturity was over 20%, indicating ample carbohydrate supply up to the cob tissue. The unloading of carbohydrate from cob to kernels was suggested as more influential on kernel-filling. Activities of sucrose synthase, ADPG-PPase and invertase were suggested to be important in contributing the high pith starch conentration early after silking. However, their low activities throughout the filling period showed no significant functional role in carbohydrate translocation and kernel-filling.

並列關鍵字

Corn Zea mays L. ； Kernel filling ； Carbohydrate metabolism ； Enzyme activity