Determination of Chlorophyll Content and Observation of Ultrastructure in Leaves of Mutants of Artocarpus heterophyllus

doi:10.3969/j.issn.1000-2561.2021.10.025

Abstract

Abstract:

Artocarpus heterophyllus is a tropical fruit, and so far there are few reports on its mutants. In this study, the leaves of A. heterophyllus were used as the experimental materials to explore the possible reasons for the albinism and regreening of the leaves. The contents of chlorophyll and chlorophyll precursors in leaf mutants and normal green leaves were determined by conventional methods. The activity of chlorophyllase was determined by Elisa kit. The ultrastructure of chloroplast was observed by a transmission electron microscope. Chlorophyll a content, chlorophyll b content, total chlorophyll content and carotenoid content produced by different leaf colors were significantly different. There was no significant difference in the content of chlorophyll synthesis precursors between the mutant and the normal green leaves. In the determination of chlorophyll enzyme activity of the leaves, although there was a significant difference in its activity, it had no significant effect on the difference in chlorophyll content. When observing the ultrastructure of chloroplasts in the leaves, it was found that the chloroplasts in the normal green leaves were intact and had a large number, and the internal structure of chloroplasts in the albino leaves and the regreening leaves was defective, because the chloroplast grana construction stage was blocked. Based on the determination of chlorophyll, chlorophyll precursor content and chlorophyll enzyme activity in the leaves, the ultrastructure of chloroplast in the leaves was observed, and the data were compared and analyzed. In this study, it was speculated that during the chlorophyll synthesis stage, the blocked synthesis of chlorophyll by pchlide and the poor chloroplast development led to the albinism and regreening of A. heterophyllus, which would provide a theoretical basis for further comprehensive study of A. heterophyllus mutants.

Key words: Artocarpus heterophyllus, chlorophyll, chlorophyll precursor substance, chlorophyll enzyme activity, ultrastructure

CLC Number:

S667.8

ZHOU Dan, LUO Can, YU Xudong, CAI Zeping, WU Fanhua. Determination of Chlorophyll Content and Observation of Ultrastructure in Leaves of Mutants of Artocarpus heterophyllus[J]. Chinese Journal of Tropical Crops, 2021, 42(10): 2935-2941.

Figures/Tables 10

Fig. 1 Seedlings of A. heterophyllus A: Normal seedling; B: Albinism seedling; C: Green seedling.

Fig. 2 Leaf color of A. heterophyllus A: Normal green leaves; B: white leaves; C: Green leaves.

Fig. 3 Synthesis pathways of chlorophyll in plants[29]

Tab. 1 Chlorophyll precursor substance content

叶绿素及其前体物质 Chlorophyll and its precursors	正常绿叶 Normal green leaves	白化叶 White leaves	返绿叶 Green leaves
ALA/(nmol•g^?1)	11.92±0.93^a	12.15±0.67^a	12.05±0.79^a
PBG/(nmol•g^?1)	6.27±0.54^a	5.85±0.34^a	6.65±0.43^a
Uro Ⅲ/(nmol•g^?1)	1.62±0.12^a	1.36±0.18^a	1.43±0.17^a
Coprogen Ⅲ/(nmol•g^?1)	0.87±0.16^a	0.90±0.18^a	0.83±0.09^a
Proto Ⅸ/(μg•g^?1)	1.24±0.26^a	1.39±0.26^a	1.47±0.37^a
Mg-Proto Ⅸ/(μg•g^?1)	0.85±0.16^a	0.91±0.18^a	0.98±0.25^a
Pchlide/(μg•g^?1)	0.51±0.06^a	0.52±0.08^a	0.49±0.14^a

Fig. 4 Relative content of chlorophyll precursors in three leaf colors The content of each substance in normal green leaves was set as 100 %, and the content of each substance in albinism leaves and returning green leaves was converted into the percentage of the corresponding content of each substance. The same lowercase letter in the same line in the graph indicates no significant difference between the two.

Tab. 2 Chlorophyll content

叶绿素 chlorophyll/(mg•g^?1)	正常绿叶 Normal green leaves	白化叶 white leaves	返绿叶 Green leaves
叶绿素a	0.956±0.105^a	0.003±0.001^c	0.159±0.028^b
叶绿素b	0.519±0.090^a	0.003±0.002^b	0.072±0.016^b
类胡萝卜素	0.161±0.013^a	0.001±0.001^b	0.005±0.003^b
叶绿素总含量	1.475±0.185^a	0.006±0.003^c	0.231±0.012^b
叶绿素a/b	1.860±0.216^a	1.511±1.304^a	2.316±0.864^a
类胡萝卜素/叶绿素总含量	0.110±0.015^a	0.169±0.145^a	0.021±0.010^a

Fig. 5 Chlorophyll content of three leaf color Different lowercase letters of the same line in the graph represent significant difference between the two (P<0.05).

Fig. 6 Biological degradation of chlorophyll

Fig. 7 Activity of chlorophyllase

Fig. 8 Ultrastructure of chloroplasts A, B: Ultrastructure of normal chloroplasts; C: Ultrastructure of chloroplast in albino leaf; D, E, F: Ultrastructure of chloroplast in regreening leaf; Nu: Nucleus; Mi: Mitochondria; CL: Chloroplast; CW: Cell wall; CM: Chloroplast membrane; P: Hungry particles; GL: Grana lamellae; SL: stroma lamella.

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