The Genetic Basis of Foliar Variegation in Three Aglaonema Species

By R.J. Henny

Aglaonema possess several unique patterns of foliar variegation which makes them ideal for breeding and genetic studies. This article presents information concerning inheritance of foliar variegation from three Aglaonema species. Aglaonema Commutatum Schott var. Picturatum 'Treubii', A. Crispum (Hort. Pitcher & Manda) Nicols. 'Chartreuse Halo'; and A. Nitidum (Jack) Kunth 'Curtisii' were the cultivars used in this study. Variegation in A. 'Treubii' consists of irregular blotches of gray/green adjacent to primary lateral veins on the upper surface of the leaf (Figure 1). Aglaonema 'Chartreuse Halo' has light green confluent blotches on each side of the leaves half way between the midrib and leaf edge (Figure 2); A. 'Curtisii' leaves have silvery stripes along the principle lateral veins (Figures 1 & 2).

Stock plants were induced to flower with Gibberellic acid treatment [21 and pollinations were made using techniques previously described for Dieffenbachia [3]. Each species was self-pollinated and intercrossed with the others. Pollinations were repeated several times because of the limited number of seeds Aglaonema flowers are capable of producing. Hybrids were evaluated for foliar variegation after approximately one year of growth following seed germination.

Results from this study are summarized in Table 1. The 9 seedlings

Table 1

Inheritance of the foliar variegation patterns from crosses Involving three species of Aglaonema.

Classes		Total Number of Seedlings	Variegation Classes
P1 (female)	P2 (male)	Total Number of Seedlings	P1	P2	P1 + P2	Green	Ratio
A. Crispum 'Chartreuse Halo' (selfed)	--	9	9	--	--	--	1:0
A. Commutatum 'Treubii (selfed)	--	54	40	--	--	14	143:1
A. Nitidum 'Curtisii (selfed)	--	16	11	--	--	5	3:1
A. c 'Chartreuse Halo'	A. n 'Curtisii'	25	14	--	11	--	1:1
A. n 'Curtisii'	A. c 'Chartreuse Halo'	34	--	19	15	--	1:1
A. c 'Chartreuse Halo'	A. c 'Treubii'	25	10	--	15	--	1:1
A. n 'Curtisii'	A. c 'Treubii'	25	8	7	5	5	1:1:1:1

(z) Number of seedlings with each type of foliar variegation pattern where P, pattern identical to female parent; P, pattern same as male parent; P1 + P2 = combination of both parental patterns superimposed on the leaves; and Green = no variegation present.

Results from this study are summarized in Table 1. The 9 seedlings obtained from selfing A. 'Chartreuse Halo' all had foliar variegation identical to their parent. In contrast, both A. 'Treubii' and A. 'Curtisii' produced a ratio of 3 variegated seedlings to one nonvariegated (green). In each case the variegated seedlings resembled the parental plants. Crossing A. 'Chartreuse Halo' re: ciprocally with A. 'Curtisii', or as fe male with A. 'Treubii' resulted in 2 classes of variegated offspring (Table 1). One-half had the 'Chartreuse Halo' pattern only, while the other half contained both the 'Chartreuse Halo' pattern plus either the 'Treubii' or 'Curtisii' Pattern depending on which was the second parent (Figures 1 &2). The only group which resulted in 4 distinct variegation classes were seedlings obtained from crossing A. 'Curtisii' with A. 'Treubii' (Table 1). One class resembled 'Curtisii' and one resembled 'Treubii' while another class showed a combination of both parental patterns. The fourth class of offspring was nonvariegated (Figure 2).

As in Dieffenbachia [11, the foliar variegation pattern from each of the three Aglaonema species in this study appeared to be under control of a single dominant gene. Aglaonema 'Treubii' and 'Curtisii' were heterozygous for variegation, whereas 'Chartreuse Halo' was homozygous. This means that all seedlings from any type of cross involving 'Chartreuse Halo' as one parent would contain the 'Chartreuse Halo' pattern. In contrast, only half the seedlings obtained from crossing 'Treubii' or 'Curtisii' with unrelated plants would be expected to contain either of their patterns.

The ability to combine the variegation pattern from both parents in some of the offspring provides great opportunity for creating unique aglaonema hybrids. Variegation being dominant and determined by a single gene makes production of such hybrids quite easy. In fact, the only limiting factor is the need to obtain an adequate number of seeds from any one cross. Time and patience are required here.